EGCG and hinokitiol already have well-known beneficial effects on human health. EGCG, or (-)-Epigallocatechin-3-gallate, is the main component in green tea. Many studies have proven its effects against oxidative stress, inflammation, and the development of cancer (2).

Hinokitiol, on the other hand, comes from the wood of certain trees such as cedar, and is an effective antibacterial (3). Commercially, it is used in cosmetics for hair, toothpaste, elimination of bad breath, etc.

But these two substances now have one more quality to brag about: they help prevent cosmetic problems. EGCG and hinokitiol reduce hyperpigmentation by lowering the amount of melanin found in the skin.

Hyperpigmentation is the darkening of the skin caused by excessive exposure to the sun, certain hormonal issues, or even acne (4). The amount of pigment in your skin, as well as the color of your hair, is determined by the amount of melanin in it.

Melanin is the name given to the natural pigments found in living beings Thus, one way to avoid unsightly pigmentation is to reduce the amount of melanin produced within the skin. This is where EGCG and hinokitiol come into play in a study conducted in Korea!

Background

The process of the production of melanin, or melanogenesis, involves many proteins, enzymes, internal factors, such as the person’s immune system, as well as external factors, such as the amount of ultraviolet radiation received.

The main proteins that were studied in this trial were: tyrosinase, Microphthalmia-associated transcription factor (MITF), and Extracellular signal-regulated kinase (ERK).

Tyrosinase is an enzyme which stimulates the production of melanin. Which means: the more tyrosinase, the more melanin is produced.

MITF is a protein which regulates many internal processes associated with pigmentation and the growth of melanin-producing cells. It actually stimulates the activity of tyrosinase. That is to say: the more MITF is present, the more active tyrosinase becomes, and the more melanin is produced.

Finally, ERK is a chain of proteins responsible for, among many other things, the regulation of melanogenesis (5). The activation of this pathway leads to less melanin; its inhibition leads to greater pigmentation.

In conclusion, in this study, these three substances were analyzed in order to determine whether EGCG and /or hinokitiol affected the production of melanin and through which specific process.

Study Summary

The material used as a substitute for human skin were Mel-Ab cells. These are lab-grown cells derived from mice which produce a lot of melanin. These cells were exposed to either EGCG, hinokitiol, or kojic acid for 4 days. Then, all of the groups were photographed with a special microscope in order to measure the amount of melanin present.

The kojic acid was used as a positive control. In other words, it has already been proven that kojic acid lowers melanin production in the skin (6); therefore, it would be a good point of comparison.

The viability of the cells was also analyzed after the 4-day treatment. The goal of studying this factor was to see if any of the substances used were cytotoxic. In other words, if they were harmful to the growth and development of the cells.

MITF, tyrosinase protein production, and ERK activation were also tested. Both separately and in combinations in order to see whether any of the substances had additive effects.

Results

It was proven that cells treated with EGCG, kojic acid, and hinokitiol were all less pigmented. That is to say, they contained less melanin. But, of the three, hinokitiol produced the lowest level of pigmentation.

EGCG and kojic acid, when used in combination, did not show any additive effect. But EGCG and hinokitiol did show an even bigger hypopigmentating effect when used together, proving that these two substances function through different processes.

None of the substances (EGCG, kojic acid, and hinokitiol) had cytotoxic effects on the mice cells.

The ERK pathway was not activated by neither hinokitiol nor EGCG. But, lower amounts of MITF and tyrosinase were found after the 4-day treatment. This proves that their melanin-reducing effects are associated with these two factors!

Lastly, it was proven that hinokitiol had the strongest effect in lowering the amount of tyrosinase in the cells.

Conclusion…

To summarize, these scientists have proven that green tea offers yet another benefit for our overall health (7). And this time, the benefit is cosmetic! But not only that: they have also pinpointed just how these substances have these marvelous effects.

The conclusion is that EGCG and hinokitiol reduce the amount of melanin in our skin, preventing problems with hyperpigmentation. And they do so by lowering the levels of MITF and tyrosinase within our cells.